AnsweredAssumed Answered

LPC1769 DAC - voltage DAC output trouble

Question asked by Jakub Papuga-Szalapski on Jan 4, 2017

Hi,

I have LPCXpresso LPC1769 Rev.D board and I need to use DAC to controll some external device.

I unsoldered L1 BK1608HS220-T from LPCXpresso LPC1769 and I connected directly my reference voltage source - REF193.

I have some troubles with LPC1769 DAC. There is no output voltage as should be.

Below is a table with results (DAC Sens = 2,9297 mV/sa = 3000 mV/1024 sa):

 

0 sa - 17,7 mV (should be 0 V)

5 sa - 32,5 mV (should be 14,6 mV)

10 sa - 46,7 mV (should be 29,3 mV

20 sa - 75,8 mV (should be 58,6 mV)

30 sa - 104,6 mV (should be 87,9 mV)

40 sa - 134,5 mV (should be 117,2 mV)

50 sa - 163,5 mV (should be 146,5 mV)

 

multimeter BRYMEN BM811A

 

There is a chart in attachement with my DAC voltage output values...

There is some nonlinear bias/offset.

 

What is wrong? Do I need something else for my DAC?

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